Heterogeneous catalyst phase(s) supported on porous metal-oxide, nitride, and carbide ceramics are widely used for a variety of electrochemical and heterogeneous reactions such as hydrogenation, dehydrogenation, and oxidation reactions, and ammonia synthesis. Superior heterogeneous catalysts require high dispersion of the catalytic phase to provide a high specific catalytic activity, as well as good stability of the catalytic phase, which provides good durability and lifetime for the catalyst. Traditional methods of supported heterogeneous catalyst preparation often lead to relatively poor initial dispersion of the catalyst and poor durability due to sintering or deactivation during service.
Platinum (Pt) and Pt alloys are among the most important and widely used metallic catalysts for both electrochemical applications, e.g. in PEM fuel cells, and heterogeneous catalysis. However, there are numerous other important heterogeneous catalysts based on other transition metals, their alloys, and metal/oxide composites to which this invention can be applied. In chemical and electrochemical applications of heterogeneous catalysts, it is highly desirable to have a high dispersion of the catalytic phase to provide a high specific catalytic activity, and good stability of the catalytic phase, which provides good durability and lifetime for the catalyst. The catalyst dispersion is a function of the preparation method and precursor, as well as the type and structure of the support material. Durability of the catalyst can be influenced by the initial dispersion, support interaction, subsequent sintering processes, chemical poisoning or dissolution, or instability of the support, among other things.
The most commonly used traditional methods of metal catalyst preparation, which include precipitation, impregnation methods and vapor phase deposition, often lead to relatively poor initial dispersion of the catalyst. This is often due to substantial phase segregation of the catalyst elements precursor during the catalyst preparation process.